Chances for Columbia ?

<p>I've always wanted to go to Columbia, but I'm worried that my below par grades in my first few years of high school may have ruined it. I don't really study that much, and I'm in a british system school (abroad) so my GPA is approximately 3.75. Which is not that good (I guess). But I've got a lot of other stuff. I volunteer to teach at a school in the rural areas every summer. I do a lot of MUNs (model United nations) and other extracurricular activities. I don't know about honors and all that, but I'm hoping to give 12 or 13 subjects in my O levels next year (And actually study for them). Oh yes, I also plan to give a couple of SAT subject tests. But that's only if I figure I have a chance.</p>